Netflix crushed its fourth-quarter earnings and the stock is up almost 9%.

The streaming-video service massively outperformed Wall Street estimates on international subscriber growth in Q4, and projected that it will add roughly 6 million new subscribers in the first quarter of 2016.

It reported revenue roughly in line with estimates, and beat big on earnings per share (EPS).

Here is how it did versus Wall Street's expectations:

EPS: $0.10, compared to $0.19 in the year-ago period, but well ahead of Wall Street estimates of $0.02 per share.

Revenue: $1.82 billion in Q4 revenue, up 23% year-on-year and just shy of the $1.83 billion expected by Wall Street.

International subscriber growth: 4.04 million versus Wall Street estimates of 3.50 million net additions, which were in line with Netflix's forecast.

Q1 subscriber-growth forecast: 6.10 million net additions, compared to 4.88 million net additions during the same period last year.

Shares of Netflix were up 8% at $116.78 in after-hours trading on Tuesday.

Netflix destroyed estimates of international subscriber growth, adding 4.04 million in the final three months of 2015. But the potential of flagging US subscriber growth is still a concern. Netflix said that its high penetration in the US seemed to be making subscriber growth more difficult, and that the introduction of chip credit cards in the US continued to be a "background issue."

Subscriber numbers are in the investor spotlight and among the most closely watched metrics in Netflix's earnings report, as some believe momentum in the US is starting to wane. Netflix made efforts to supercharge subscriber growth by going live in 130 more countries earlier this month, bringing the total to 190 — in effect, the entire world except China.

The company said in a letter to shareholders on Tuesday that while the opportunity is large, Netflix's growth in new markets will unfold over "many years."

"We are starting by primarily targeting outward‐looking, affluent consumers with international credit cards and smartphones. As with every market we've launched, our approach is to listen, learn and improve rapidly, adding more content," Netflix said.

With regards to China, the last major market Netflix is missing, the company said that it had "work and uncertainty ahead," and characterized its expectations as "modest and long‐term."

Netflix generated $60 million in operating income during the last three months of the year, and said it expects "similar modest" operating income in Q1 as it invests in international expansion. Netflix said that it continues to expect "material global profits" beginning in 2017.